ASP.NET通过SqlCommand、SqlDataReader 读取数据库有关问题

using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.Data.SqlClient;public partial class admin_zpxg : System.Web.UI.Page{    SqlConnection con;    string sqlcon = ConfigurationManager.ConnectionStrings["rjs_admin"].ConnectionString;    private static int productID;    protected void Page_Load(object sender, EventArgs e)    {        if (!IsPostBack)        {            productID = Convert.ToInt32(Request.QueryString["prodID"]);            contentdatabind();        }    }    protected void contentdatabind()    {        con = new SqlConnection(sqlcon);        con.Open();        string strsql = "select * from [Product] where prodID='" + productID + "'";        SqlCommand cmd = new SqlCommand(strsql,con);        SqlDataReader dr = cmd.ExecuteReader();        if (dr.Read())        {            //this.txtname.Text = dr["prodName"].ToString();            //this.ddlgroup.Text = dr["groupName"].ToString();            //this.txtimgpath.Text = dr["prodImages"].ToString();            //this.prodauthor.Text = dr["prodAuthor"].ToString();            //this.prodintroduce.Text = dr["prodIntroduce"].ToString();            this.txtname.Text = "哈哈";            //我测试了下，确定是Read没有读取，把上面的注释去掉的话会报错、说是没有读取到。。。        }        else        {            this.txtname.Text = "啊啊啊啊";        }        con.Close();    }}

 con = new SqlConnection(sqlcon);        con.Open();        string strsql = "select * from [Product] where prodID='" + productID + "'";         SqlDataAdapter sda = new SqlDataAdapter(strsql,con );           DataSet ds=new  DataSet();         sda.fill(ds);           if (ds.table[0].rows.count>0)        {                       this.txtname.Text = ds.table[0].rows[0]["prodName"].TOString();           }        else        {            this.txtname.Text = "啊啊啊啊";        }        con.Close();
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引用:
string strsql = "select * from [Product] where prodID='" + productID + "'";

这里加断点，然后看strsql值是什么？

我以前也遇到过这个情况，但是用try catch能行就没管，这次是要发誓解开心里的疙瘩啊啊啊~`

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打端点调试吧。。。一步一步看
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因为存在null值，所以读不出来，是先判断一下是否为null
标准的做法

C# code
        string strsql = "select prodName,groupName,prodImages,prodAuthor,prodIntroduce from [Product] where prodID='1'";        SqlCommand cmd = new SqlCommand(strsql,con);        using (SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))        {            if (dr.Read())            {                this.txtname.Text = dr.IsDBNull(0) ? string.Empty : dr.GetString(0);                this.ddlgroup.Text = dr.IsDBNull(1) ? string.Empty : dr.GetString(1);                this.txtimgpath.Text = dr.IsDBNull(2) ? string.Empty : dr.GetString(2);                this.prodauthor.Text = dr.IsDBNull(3) ? string.Empty : dr.GetString(3);                this.prodintroduce.Text = dr.IsDBNull(4) ? string.Empty : dr.GetString(4);            }        }